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Forget invisibility or flight: the superpower we all want is the ability to do several things at once. Unlike other superpowers, however, being able to multitask is now widely regarded as a basic requirement for employability. Some of us sport computers with multiple screens, to allow tweeting while trading pork bellies and frozen orange juice. Others make do with reading a Kindle while poking at a smartphone and glancing at a television in the corner with its two rows of scrolling subtitles. We think nothing of sending an email to a colleague to suggest a quick coffee break, because we can feel confident that the email will be read within minutes.

All this is simply the way the modern world works. Multitasking is like being able to read or add up, so fundamental that it is taken for granted. Doing one thing at a time is for losers — recall Lyndon Johnson’s often bowdlerised dismissal of Gerald Ford: “He can’t fart and chew gum at the same time.”

Podcast

Modern life forces us to do a multitude of things at once - but can we? Should we? Tim Harford, the Undercover Economist who has 150 things on his to-do list, talks to the editor of the FT Weekend Magazine about the myths, science and history of multi-tasking - and how to do it well.

The rise of multitasking is fuelled by technology, of course, and by social change as well. Husbands and wives no longer specialise as breadwinners and homemakers; each must now do both. Work and play blur. Your friends can reach you on your work email account at 10 o’clock in the morning, while your boss can reach you on your mobile phone at 10 o’clock at night. You can do your weekly shop sitting at your desk and you can handle a work query in the queue at the supermarket.

This is good news in many ways — how wonderful to be able to get things done in what would once have been wasted time! How delightful the variety of it all is! No longer must we live in a monotonous, Taylorist world where we must painstakingly focus on repetitive tasks until we lose our minds.

And yet we are starting to realise that the blessings of a multitasking life are mixed. We feel overwhelmed by the sheer number of things we might plausibly be doing at any one time, and by the feeling that we are on call at any moment.

And we fret about the unearthly appetite of our children to do everything at once, flipping through homework while chatting on WhatsApp, listening to music and watching Game of Thrones. (According to a recent study by Sabrina Pabilonia of the US Bureau of Labor Statistics, for over half the time that high-school students spend doing homework, they are also listening to music, watching TV or otherwise multitasking. That trend is on the increase.) Can they really handle all these inputs at once? They seem to think so, despite various studies suggesting otherwise.

And so a backlash against multitasking has begun — a kind of Luddite self-help campaign. The poster child for uni-tasking was launched on the crowdfunding website Kickstarter in December 2014. For $499 — substantially more than a multifunctional laptop — “The Hemingwrite” computer promised a nice keyboard, a small e-ink screen and an automatic cloud back-up. You couldn’t email on the Hemingwrite. You couldn’t fool around on YouTube, and you couldn’t read the news. All you could do was type. The Hemingwrite campaign raised over a third of a million dollars.

The Hemingwrite (now rebranded the Freewrite) represents an increasingly popular response to the multitasking problem: abstinence. Programs such as Freedom and Self-Control are now available to disable your browser for a preset period of time. The popular blogging platform WordPress offers “distraction-free writing”. The Villa Stéphanie, a hotel in Baden-Baden, offers what has been branded the “ultimate luxury”: a small silver switch beside the hotel bed that will activate a wireless blocker and keep the internet and all its temptations away.

The battle lines have been drawn. On one side: the culture of the modern workplace, which demands that most of us should be open to interruption at any time. On the other, the uni-tasking refuseniks who insist that multitaskers are deluding themselves, and that focus is essential. Who is right?

The ‘cognitive cost’

There is ample evidence in favour of the proposition that we should focus on one thing at a time. Consider a study led by David Strayer, a psychologist at the University of Utah. In 2006, Strayer and his colleagues used a high-fidelity driving simulator to compare the performance of drivers who were chatting on a mobile phone to drivers who had drunk enough alcohol to be at the legal blood-alcohol limit in the US. Chatting drivers didn’t adopt the aggressive, risk-taking style of drunk drivers but they were unsafe in other ways. They took much longer to respond to events outside the car, and they failed to notice a lot of the visual cues around them. Strayer’s infamous conclusion: driving while using a mobile phone is as dangerous as driving while drunk.

Less famous was Strayer’s finding that it made no difference whether the driver was using a handheld or hands-free phone. The problem with talking while driving is not a shortage of hands. It is a shortage of mental bandwidth.

Yet this discovery has made little impression either on public opinion or on the law. In the United Kingdom, for example, it is an offence to use a hand-held phone while driving but perfectly legal if the phone is used hands-free. We’re happy to acknowledge that we only have two hands but refuse to admit that we only have one brain.

Another study by Strayer, David Sanbonmatsu and others, suggested that we are also poor judges of our ability to multitask. The subjects who reported doing a lot of multitasking were also the ones who performed poorly on tests of multitasking ability. They systematically overrated their ability to multitask and they displayed poor impulse control. In other words, wanting to multitask is a good sign that you should not be multitasking.

We may not immediately realise how multitasking is hampering us. The first time I took to Twitter to comment on a public event was during a televised prime-ministerial debate in 2010. The sense of buzz was fun; I could watch the candidates argue and the twitterati respond, compose my own 140-character profundities and see them being shared. I felt fully engaged with everything that was happening. Yet at the end of the debate I realised, to my surprise, that I couldn’t remember anything that Brown, Cameron and Clegg had said.

We fret as our children flip through homework, chatting on WhatsApp and listening to music. Can they really handle all these inputs at once?

A study conducted at UCLA in 2006 suggests that my experience is not unusual. Three psychologists, Karin Foerde, Barbara Knowlton and Russell Poldrack, recruited students to look at a series of flashcards with symbols on them, and then to make predictions based on patterns they had recognised. Some of these prediction tasks were done in a multitasking environment, where the students also had to listen to low- and high-pitched tones and count the high-pitched ones. You might think that making predictions while also counting beeps was too much for the students to handle. It wasn’t. They were equally competent at spotting patterns with or without the note-counting task.

But here’s the catch: when the researchers then followed up by asking more abstract questions about the patterns, the cognitive cost of the multitasking became clear. The students struggled to answer questions about the predictions they’d made in the multitasking environment. They had successfully juggled both tasks in the moment — but they hadn’t learnt anything that they could apply in a different context.

That’s an unnerving discovery. When we are sending email in the middle of a tedious meeting, we may nevertheless feel that we’re taking in what is being said. A student may be confident that neither Snapchat nor the live football is preventing them taking in their revision notes. But the UCLA findings suggest that this feeling of understanding may be an illusion and that, later, we’ll find ourselves unable to remember much, or to apply our knowledge flexibly. So, multitasking can make us forgetful — one more way in which multitaskers are a little bit like drunks.

Early multitaskers

All this is unnerving, given that the modern world makes multitasking almost inescapable. But perhaps we shouldn’t worry too much. Long before multitasking became ubiquitous, it had a long and distinguished history.

In 1958, a young psychologist named Bernice Eiduson embarked on an long-term research project — so long-term, in fact, that Eiduson died before it was completed. Eiduson studied the working methods of 40 scientists, all men. She interviewed them periodically over two decades and put them through various psychological tests. Some of these scientists found their careers fizzling out, while others went on to great success. Four won Nobel Prizes and two others were widely regarded as serious Nobel contenders. Several more were invited to join the National Academy of Sciences.

After Eiduson died, some of her colleagues published an analysis of her work. These colleagues, Robert Root-Bernstein, Maurine Bernstein and Helen Garnier, wanted to understand what determined whether a scientist would have a long productive career, a combination of genius and longevity.

There was no clue in the interviews or the psychological tests. But looking at the early publication record of these scientists — their first 100 published research papers — researchers discovered a pattern: the top scientists were constantly changing the focus of their research.

Over the course of these first 100 papers, the most productive scientists covered five different research areas and moved from one of these topics to another an average of 43 times. They would publish, and change the subject, publish again, and change the subject again. Since most scientific research takes an extended period of time, the subjects must have overlapped. The secret to a long and highly productive scientific career? It’s multitasking.

Charles Darwin thrived on spinning multiple plates

Charles Darwin thrived on spinning multiple plates. He began his first notebook on “transmutation of species” two decades before The Origin of Species was published. His A Biographical Sketch of an Infant was based on notes made after his son William was born; William was 37 when he published. Darwin spent nearly 20 years working on climbing and insectivorous plants. And Darwin published a learned book on earthworms in 1881, just before his death. He had been working on it for 44 years. When two psychologists, Howard Gruber and Sara Davis, studied Darwin and other celebrated artists and scientists they concluded that such overlapping interests were common.

Another team of psychologists, led by Mihaly Csikszentmihalyi, interviewed almost 100 exceptionally creative people from jazz pianist Oscar Peterson to science writer Stephen Jay Gould to double Nobel laureate, the physicist John Bardeen. Csikszentmihalyi is famous for developing the idea of “flow”, the blissful state of being so absorbed in a challenge that one loses track of time and sets all distractions to one side. Yet every one of Csikszentmihalyi’s interviewees made a practice of keeping several projects bubbling away simultaneously.

Just internet addiction?

If the word “multitasking” can apply to both Darwin and a teenager with a serious Instagram habit, there is probably some benefit in defining our terms. There are at least four different things we might mean when we talk about multitasking. One is genuine multitasking: patting your head while rubbing your stomach; playing the piano and singing; farting while chewing gum. Genuine multitasking is possible, but at least one of the tasks needs to be so practised as to be done without thinking.

Then there’s the challenge of creating a presentation for your boss while also fielding phone calls for your boss and keeping an eye on email in case your boss wants you. This isn’t multitasking in the same sense. A better term is task switching, as our attention flits between the presentation, the telephone and the inbox. A great deal of what we call multitasking is in fact rapid task switching.

Task switching is often confused with a third, quite different activity — the guilty pleasure of disappearing down an unending click-hole of celebrity gossip and social media updates. There is a difference between the person who reads half a page of a journal article, then stops to write some notes about a possible future project, then goes back to the article — and someone who reads half a page of a journal article before clicking on bikini pictures for the rest of the morning. “What we’re often calling multitasking is in fact internet addiction,” says Shelley Carson, a psychologist and author of Your Creative Brain. “It’s a compulsive act, not an act of multitasking.”

A final kind of multitasking isn’t a way of getting things done but simply the condition of having a lot of things to do. The car needs to be taken in for a service. Your tooth is hurting. The nanny can’t pick up the kids from school today. There’s a big sales meeting to prepare for tomorrow, and your tax return is due next week. There are so many things that have to be done, so many responsibilities to attend to. Having a lot of things to do is not the same as doing them all at once. It’s just life. And it is not necessarily a stumbling block to getting things done — as Bernice Eiduson discovered as she tracked scientists on their way to their Nobel Prizes.

The fight for focus

These four practices — multitasking, task switching, getting distracted and managing multiple projects — all fit under the label “multitasking”. This is not just because of a simple linguistic confusion. The versatile networked devices we use tend to blur the distinction, serving us as we move from task to task while also offering an unlimited buffet of distractions. But the different kinds of multitasking are linked in other ways too. In particular, the highly productive practice of having multiple projects invites the less-than-productive habit of rapid task switching.

To see why, consider a story that psychologists like to tell about a restaurant near Berlin University in the 1920s. (It is retold in Willpower, a book by Roy Baumeister and John Tierney.) The story has it that when a large group of academics descended upon the restaurant, the waiter stood and calmly nodded as each new item was added to their complicated order. He wrote nothing down, but when he returned with the food his memory had been flawless. The academics left, still talking about the prodigious feat; but when one of them hurried back to retrieve something he’d left behind, the waiter had no recollection of him. How could the waiter have suddenly become so absent-minded? “Very simple,” he said. “When the order has been completed, I forget it.”

One member of the Berlin school was a young experimental psychologist named Bluma Zeigarnik. Intrigued, she demonstrated that people have a better recollection of uncompleted tasks. This is called the “Zeigarnik effect”: when we leave things unfinished, we can’t quite let go of them mentally. Our subconscious keeps reminding us that the task needs attention.

The Zeigarnik effect may explain the connection between facing multiple responsibilities and indulging in rapid task switching. We flit from task to task to task because we can’t forget about all of the things that we haven’t yet finished. We flit from task to task to task because we’re trying to get the nagging voices in our head to shut up.

When we leave things unfinished, we can’t quite let go of them mentally. The essence of the 'Zeigarnik effect', named after Bluma Zeigarnik, the psychologist who first identified this phenomenon in the 1920s

Of course, there is much to be said for “focus”. But there is much to be said for copperplate handwriting, too, and for having a butler. The world has moved on. There’s something appealing about the Hemingwrite and the hotel room that will make the internet go away, but also something futile.

It is probably not true that Facebook is all that stands between you and literary greatness. And in most office environments, the Hemingwrite is not the tool that will win you promotion. You are not Ernest Hemingway, and you do not get to simply ignore emails from your colleagues.

If focus is going to have a chance, it’s going to have to fight an asymmetric war. Focus can only survive if it can reach an accommodation with the demands of a multitasking world.

Loops and lists

The word “multitasking” wasn’t applied to humans until the 1990s, but it has been used to describe computers for half a century. According to the Oxford English Dictionary, it was first used in print in 1966, when the magazine Datamation described a computer capable of appearing to perform several operations at the same time.

Just as with humans, computers typically create the illusion of multitasking by switching tasks rapidly. Computers perform the switching more quickly, of course, and they don’t take 20 minutes to get back on track after an interruption.

Nor does a computer fret about what is not being done. While rotating a polygon and sending text to the printer, it feels no guilt that the mouse has been left unchecked for the past 16 milliseconds. The mouse’s time will come. Being a computer means never having to worry about the Zeigarnik effect.

David Allen, author of 'Getting Things Done'. 'Saying “I’ll get back to you about that” opens a loop in your brain’

Is there a lesson in this for distractible sacks of flesh like you and me? How can we keep a sense of control despite the incessant guilt of all the things we haven’t finished?

“Whenever you say to someone, ‘I’ll get back to you about that’, you just opened a loop in your brain,” says David Allen. Allen is the author of a cult productivity book called Getting Things Done. “That loop will keep spinning until you put a placeholder in a system you can trust.”

Modern life is always inviting us to open more of those loops. It isn’t necessarily that we have more work to do, but that we have more kinds of work that we ought to be doing at any given moment. Tasks now bleed into each other unforgivingly. Whatever we’re doing, we can’t escape the sense that perhaps we should be doing something else. It’s these overlapping possibilities that take the mental toll.

The principle behind Getting Things Done is simple: close the open loops. The details can become rather involved but the method is straightforward. For every single commitment you’ve made to yourself or to someone else, write down the very next thing you plan to do. Review your lists of next actions frequently enough to give you confidence that you won’t miss anything.

This method has a cult following, and practical experience suggests that many people find it enormously helpful — including me (see below). Only recently, however, did the psychologists E J Masicampo and Roy Baumeister find some academic evidence to explain why people find relief by using David Allen’s system. Masicampo and Baumeister found that you don’t need to complete a task to banish the Zeigarnik effect. Making a specific plan will do just as well. Write down your next action and you quiet that nagging voice at the back of your head. You are outsourcing your anxiety to a piece of paper.

A creative edge?

It is probably a wise idea to leave rapid task switching to the computers. Yet even frenetic flipping between Facebook, email and a document can have some benefits alongside the costs.

The psychologist Shelley Carson and her student Justin Moore recently recruited experimental subjects for a test of rapid task switching. Each subject was given a pair of tasks to do: crack a set of anagrams and read an article from an academic journal. These tasks were presented on a computer screen, and for half of the subjects they were presented sequentially — first solve the anagrams, then read the article. For the other half of the experimental group, the computer switched every two-and-a-half minutes between the anagrams and the journal article, forcing the subjects to change mental gears many times.

Unsurprisingly, task switching slowed the subjects down and scrambled their thinking. They solved fewer anagrams and performed poorly on a test of reading comprehension when forced to refocus every 150 seconds.

But the multitasking treatment did have a benefit. Subjects who had been task switching became more creative. To be specific, their scores on tests of “divergent” thinking improved. Such tests ask subjects to pour out multiple answers to odd questions. They might be asked to think of as many uses as possible for a rolling pin or to list all the consequences they could summon to mind of a world where everyone has three arms. Involuntary multitaskers produced a greater volume and variety of answers, and their answers were more original too.

“It seems that switching back and forth between tasks primed people for creativity,” says Carson, who is an adjunct professor at Harvard. The results of her work with Moore have not yet been published, and one might reasonably object that such tasks are trivial measures of creativity. Carson responds that scores on these laboratory tests of divergent thinking are correlated with substantial creative achievements such as publishing a novel, producing a professional stage show or creating an award-winning piece of visual art. For those who insist that great work can only be achieved through superhuman focus, think long and hard on this discovery.

Carson and colleagues have found an association between significant creative achievement and a trait psychologists term “low latent inhibition”. Latent inhibition is the filter that all mammals have that allows them to tune out apparently irrelevant stimuli. It would be crippling to listen to every conversation in the open-plan office and the hum of the air conditioning, while counting the number of people who walk past the office window. Latent inhibition is what saves us from having to do so. These subconscious filters let us walk through the world without being overwhelmed by all the different stimuli it hurls at us.

And yet people whose filters are a little bit porous have a big creative edge. Think on that, uni-taskers: while you busily try to focus on one thing at a time, the people who struggle to filter out the buzz of the world are being reviewed in The New Yorker.

“You’re letting more information into your cognitive workspace, and that information can be consciously or unconsciously combined,” says Carson. Two other psychologists, Holly White and Priti Shah, found a similar pattern for people suffering from attention deficit hyperactivity disorder (ADHD).

Think long on this, uni-taskers: the people who struggle to filter out the buzz of the world are being reviewed in The New Yorker

It would be wrong to romanticise potentially disabling conditions such as ADHD. All these studies were conducted on university students, people who had already demonstrated an ability to function well. But their conditions weren’t necessarily trivial — to participate in the White/Shah experiment, students had to have a clinical diagnosis of ADHD, meaning that their condition was troubling enough to prompt them to seek professional help.

It’s surprising to discover that being forced to switch tasks can make us more creative. It may be still more surprising to realise that in an age where we live under the threat of constant distraction, people who are particularly prone to being distracted are flourishing creatively.

Perhaps we shouldn’t be entirely surprised. It’s easier to think outside the box if the box is full of holes. And it’s also easier to think outside the box if you spend a lot of time clambering between different boxes. “The act of switching back and forth can grease the wheels of thought,” says John Kounios, a professor of psychology at Drexel University.

Kounios, who is co-author of The Eureka Factor, suggests that there are at least two other potentially creative mechanisms at play when we switch between tasks. One is that the new task can help us forget bad ideas. When solving a creative problem, it’s easy to become stuck because we think of an incorrect solution but simply can’t stop returning to it. Doing something totally new induces “fixation forgetting”, leaving us free to find the right answer.

Another is “opportunistic assimilation”. This is when the new task prompts us to think of a solution to the old one. The original Eureka moment is an example.

As the story has it, Archimedes was struggling with the task of determining whether a golden wreath truly was made of pure gold without damaging the ornate treasure. The solution was to determine whether the wreath had the same volume as a pure gold ingot with the same mass; this, in turn, could be done by submerging both the wreath and the ingot to see whether they displaced the same volume of water.

This insight, we are told, occurred to Archimedes while he was having a bath and watching the water level rise and fall as he lifted himself in and out. And if solving such a problem while having a bath isn’t multitasking, then what is?

Six ways to be a master of multitasking

1. Be mindful

“The ideal situation is to be able to multitask when multitasking is appropriate, and focus when focusing is important,” says psychologist Shelley Carson. Tom Chatfield, author of Live This Book, suggests making two lists, one for activities best done with internet access and one for activities best done offline. Connecting and disconnecting from the internet should be deliberate acts.

2. Write it down

The essence of David Allen’s Getting Things Done is to turn every vague guilty thought into a specific action, to write down all of the actions and to review them regularly. The point, says Allen, is to feel relaxed about what you’re doing — and about what you’ve decided not to do right now — confident that nothing will fall through the cracks.

3. Tame your smartphone

The smartphone is a great servant and a harsh master. Disable needless notifications — most people don’t need to know about incoming tweets and emails. Set up a filing system within your email so that when a message arrives that requires a proper keyboard to answer — ie 50 words or more — you can move that email out of your inbox and place it in a folder where it will be waiting for you when you fire up your computer.

4. Focus in short sprints

The “Pomodoro Technique” — named after a kitchen timer — alternates focusing for 25 minutes and breaking for five minutes, across two-hour sessions. Productivity guru Merlin Mann suggests an “email dash”, where you scan email and deal with urgent matters for a few minutes each hour. Such ideas let you focus intensely while also switching between projects several times a day.

5. Procrastinate to win

If you have several interesting projects on the go, you can procrastinate over one by working on another. (It worked for Charles Darwin.) A change is as good as a rest, they say — and as psychologist John Kounios explains, such task switching can also unlock new ideas.

6. Cross-fertilise

“Creative ideas come to people who are interdisciplinary, working across different organisational units or across many projects,” says author and research psychologist Keith Sawyer. (Appropriately, Sawyer is also a jazz pianist, a former management consultant and a sometime game designer for Atari.) Good ideas often come when your mind makes unexpected connections between different fields.

Tim Harford’s To-Do Lists

David Allen’s Getting Things Done system — or GTD — has reached the status of a religion among some productivity geeks. At its heart, it’s just a fancy to-do list, but it’s more powerful than a regular list because it’s comprehensive, specific and designed to prompt you when you need prompting. Here’s how I make the idea work for me.

Write everything down. I use Google Calendar for appointments and an electronic to-do list called Remember the Milk, plus an ad hoc daily list on paper. The details don’t matter. The principle is never to carry a mental commitment around in your head.

Make the list comprehensive. Mine currently has 151 items on it. (No, I don’t memorise the number. I just counted.)

Keep the list fresh. The system works its anxiety-reducing magic best if you trust your calendar and to-do list to remind you when you need reminding. I spend about 20 minutes once a week reviewing the list to note incoming deadlines and make sure the list is neither missing important commitments nor cluttered with stale projects. Review is vital — the more you trust your list, the more you use it. The more you use it, the more you trust it.

List by context as well as topic. It’s natural to list tasks by topic or project — everything associated with renovating the spare room, for instance, or next year’s annual away-day. I also list them by context (this is easy on an electronic list). Things I can do when on a plane; things I can only do when at the shops; things I need to talk about when I next see my boss.

Be specific about the next action. If you’re just writing down vague reminders, the to-do list will continue to provoke anxiety. Before you write down an ill-formed task, take the 15 seconds required to think about exactly what that task is.

Share your own tips for multitasking on the FT’s Facebook page. We will print the best advice in next week’s magazine